Browse Forums Owner Builder Forum 1 Jan 07, 2018 9:52 pm Twas wondering if anyone can help. I've been looking at insulation batts for walls. Researching on the net, R2 cost about $3.80/ M² and R2.5 is double at about $7.60 /M². They are the same depth at 90mm, one is denser I assume. I'm in Sydney, near the coast but not on it and I was wondering is it worth the the extra cost, which is not going to break the bank but I can think of other things that I would like to spend it on if it is only a negligible difference? It will be in a brick veneer, wrapped with double glazed windows. For the all external walls it is about $900 or $1800 for the R2.5. I was thinking that the 2.5 might be a bit stiffer and maybe they wouldn't slump as easily over time in between the studs giving better long term results. Thanks for any input. Bruce Re: Insulation Batts 2Jan 09, 2018 9:25 pm Considering you are already investing into double glazed windows, the obvious question is why not to have a bit better insulation (and wall acoustics too)? On the other side, I would rather focus on how well the batts are installed and how well your windows/doors are air sealed. Another point to think about: you would probably won't be able to notice much difference between R2.0 and R2.5 heating/cooling bill wise initially, however, it may pay off in the long run (e.g. in 10 years time). Re: Insulation Batts 3Jan 10, 2018 7:40 am alexp79 Considering you are already investing into double glazed windows, the obvious question is why not to have a bit better insulation (and wall acoustics too)? On the other side, I would rather focus on how well the batts are installed and how well your windows/doors are air sealed. Another point to think about: you would probably won't be able to notice much difference between R2.0 and R2.5 heating/cooling bill wise initially, however, it may pay off in the long run (e.g. in 10 years time). I probably will go with the 2.5, it's only a small extra cost but small things do add up over the build. I agree, installation of the product is the most important thing to get right. I will be placing acoustic insulation where it is required. Thanks for your reply Re: Insulation Batts 4Feb 03, 2018 1:12 pm To be honest the money difference indicates you should go with the better, but I really can't see it making much of a difference. In Sydney when we had days with 40+ temps, do you really think it would of helped having the 2.5? Re: Insulation Batts 5Feb 03, 2018 2:56 pm lackey To be honest the money difference indicates you should go with the better, but I really can't see it making much of a difference. In Sydney when we had days with 40+ temps, do you really think it would of helped having the 2.5? Going with R2.5 over R2.0 is even more cost-effective when temperatures are very high (35+) or very low (10-). At that level (especially with brick veneer where the only insulation is in the wall batts) an extra 0.5 R-value makes a significant difference in required heating/cooling loads, and hence both comfort and energy usage. The higher the peak temperature, the greater the long-term payoff from even small increases in insulation. For a lousy couple of thousand bucks, if 40+ temperatures are expected then it's a no-brainer to spend the extra on the upgrade. You'd make that back in the reduced electricity bills in the first few years (and be more comfortable while doing so). Of course, the insulation should be properly installed to be fully effective, e.g with no uninsulated gaps between wall and ceiling, batts installed without gaps and without being compressed, ceiling batts properly cut to shape and not just pushed out of the way by following trades (e.g. to install ducting), etc. Re: Insulation Batts 6Feb 03, 2018 4:11 pm algernon lackey To be honest the money difference indicates you should go with the better, but I really can't see it making much of a difference. In Sydney when we had days with 40+ temps, do you really think it would of helped having the 2.5? Going with R2.5 over R2.0 is even more cost-effective when temperatures are very high (35+) or very low (10-). At that level (especially with brick veneer where the only insulation is in the wall batts) an extra 0.5 R-value makes a significant difference in required heating/cooling loads, and hence both comfort and energy usage. The higher the peak temperature, the greater the long-term payoff from even small increases in insulation. For a lousy couple of thousand bucks, if 40+ temperatures are expected then it's a no-brainer to spend the extra on the upgrade. You'd make that back in the reduced electricity bills in the first few years (and be more comfortable while doing so). Of course, the insulation should be properly installed to be fully effective, e.g with no uninsulated gaps between wall and ceiling, batts installed without gaps and without being compressed, ceiling batts properly cut to shape and not just pushed out of the way by following trades (e.g. to install ducting), etc. Many air cons barely cope with higher temps, batts won't do much as in you won't get twice the benefit from twice the price.. Re: Insulation Batts 7Feb 03, 2018 4:37 pm lackey Many air cons barely cope with higher temps, batts won't do much as in you won't get twice the benefit from twice the price.. Yep, many airconditioners do struggle with really high temperatures in poorly-insulated houses, which is all the more reason to upgrade the house insulation. An airconditioner that does quite well in a 8-star house might struggle in a 6-star house in the same situation (and not cope at all with the typical Australian 0- to 1- star house). More insulation = less heat transfer = less load on the aircon. It's like trying to run an oven or fridge with the door open vs. closed (or, for that matter, running a cheaper oven or fridge with less internal insulation than a higher-quality model). Even before construction has finished, well-insulated houses are often able to offset any extra insulation costs by using smaller (hence cheaper) aircon setups, because they don't need the extra power to make up for poor insulation. And that's in addition to the much lower operating costs. Yes, insulation costs are non-linear, i.e. you'll pay more to go from R2.5 to 3.0 than from R2.0 to 2.5, and so there is a point at which the extra insulation isn't warranted by the increasing costs. Suffice to say, though, that bog-standard Australian brick veneer houses don't usually get anywhere near that point (by my calcs, the tipping point for walls is somewhere around R4.0-R4.5 based on the last quote I saw for batts a couple of months ago). Re: Insulation Batts 8Feb 03, 2018 4:49 pm The bottom line, If moving from R2.0 to R2.5 in wall insulation batts will allow you to install let's say normal 14kW aircon instead of 3 phase 18kW, it is a no-brainer investment. Ideally, you would need to run it through your BASIX modeling to understand the potential advantages you can get. On the other side, even if your insulation is perfectly fitted, wood studs themselves will be providing maximum of R1.0 anyway, and, hence, your overall insulation will still be lower. The best option will be to to use rigid (e.g. XPS) or blanket type of insulation around the frame, but this will be creating a major of issues/problems with brick veneer. Re: Insulation Batts 9Apr 25, 2018 9:10 pm Searching4 knowledge Twas wondering if anyone can help. I've been looking at insulation batts for walls. Researching on the net, R2 cost about $3.80/ M² and R2.5 is double at about $7.60 /M². They are the same depth at 90mm, one is denser I assume. I'm in Sydney, near the coast but not on it and I was wondering is it worth the the extra cost, which is not going to break the bank but I can think of other things that I would like to spend it on if it is only a negligible difference? It will be in a brick veneer, wrapped with double glazed windows. For the all external walls it is about $900 or $1800 for the R2.5. I was thinking that the 2.5 might be a bit stiffer and maybe they wouldn't slump as easily over time in between the studs giving better long term results. Thanks for any input. Bruce insulation is one of the most important things in a home , its too often overlooked in australia and almost never installed properly. you should have an energy evaluation and report on your home to find out what is the best method. r values dont matter if it isnt installed correctly . Re: Insulation Batts 10Jul 13, 2018 8:00 pm Hey here is an idea I came up with today. I have a raked ceiling that gets to 40 degrees + in the summer under an cement sheet roof. No insulation at all between roof and ceiling material. (used to be a carport and previous owner just turned it into a room. Anyway, I thought to put in some ceiling insulation,...but cannot find what is best. Extruded foil is expensive and ugly...but then , I plan to put gyprock over the wonderful looking raked beams. it is either that or pay air con all summer.( and heating in thewinter) So I say some blanket insulation without foil at bunnings and thought R 2.0 ...not very good, but if I attach some foil sarking to the rolls of insulation that may improve the R value. Any thoughts on that idea. ( I haven't seen better than R 2.,0 rools of ceiling insulation with foil attached. thanks for any input. Re: Insulation Batts 11Jul 13, 2018 8:49 pm If you're gyprocking anyway, you could install batts and hold them in place with string until you get the gyprock up. How deep are the beams? Or if you need to batten out the rafters before gyprocking you might be able to sit the batts on top of the battens. Re: Insulation Batts 12Jul 14, 2018 2:05 pm Thanks for the reply. Yes double up on thickness of battens was an idea. beams are 180mm. What do you think on my idea of laying sarking under the insulation? (silver side down) A couple of my plasterer friends, think that screwwing plaster board to beams is NOT a good idea due to expansion and possible screw heads changing position (pulling thru) and then you need to plaster again. They both recommend metal battens and put gyprock into metal battens. A more solid solution. However, my beams are 30 years old, indoors too....so I think their ideas do not have a lot of merit. Rae Re: Insulation Batts 13Jul 14, 2018 7:46 pm raelph Thanks for the reply. Yes double up on thickness of battens was an idea. beams are 180mm. What do you think on my idea of laying sarking under the insulation? (silver side down) A couple of my plasterer friends, think that screwwing plaster board to beams is NOT a good idea due to expansion and possible screw heads changing position (pulling thru) and then you need to plaster again. They both recommend metal battens and put gyprock into metal battens. A more solid solution. However, my beams are 30 years old, indoors too....so I think their ideas do not have a lot of merit. Rae Like this I presume. I was told they do this for long runs and in wet areas only. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Re: Insulation Batts 14Jul 15, 2018 9:49 am raelph Thanks for the reply. Yes double up on thickness of battens was an idea. beams are 180mm. What do you think on my idea of laying sarking under the insulation? (silver side down) A couple of my plasterer friends, think that screwwing plaster board to beams is NOT a good idea due to expansion and possible screw heads changing position (pulling thru) and then you need to plaster again. They both recommend metal battens and put gyprock into metal battens. A more solid solution. However, my beams are 30 years old, indoors too....so I think their ideas do not have a lot of merit. Rae With 180mm space you could fit slightly compressed R3.5 batts (185mm) or R3.0 (165mm), which would make a very noticeable difference. Not sure foil would be necessary, you also need to be careful using foil in ceilings, if there are any electrical penetrations (lights etc) as the foil is conductive. I would say battens would be a must. Found the answer. The recommended distance is .... 1 5952 I am saying that double brick has similar thermal performance due to thermal mass effect. It will be still very interesting to see the state of your framing after 10-15… 10 29662 |